Flat panel liquid crystal displays, particularly of the type having individual liquid crystal elements or pixels arranged in an orthogonal row and column arrangement are well known and useful in a variety of applications. In transmissive displays using twisted nematic liquid crystals, polarizers are located on each side of the panel and a light source is positioned behind the panel. Due to the nature of the arrangement of molecules in nematic liquid crystals, light from a particular off-axis direction is not equally affected as light from other off-axis directions. If a display is in a mode to block light from being transmitted through it, the result, because of this effect is to not equally block the light from all axial directions.
It would, obviously, be useful to illuminate the flat panel displays with light normal to the cell and collimated, thereby avoiding the loss of contrast (lack of blocking) in viewing the cell from a particular direction.
It is therefore a principal objective of the invention to provide a collimated light source for all axes or particular axes off the normal for a flat panel liquid crystal display.
Yet another objective of the invention is to provide a collimated light source for liquid crystal displays utilizing tapered light pipes.
Still another objective of the invention is to provide a collimated light source for flat panel liquid display which utilizes a combination of light pipes and an integrating light sphere.
Other objectives and advantages of the invention will become apparent as the description thereof proceeds.